Process of forming pinking-cutters.



No. 655,484. Patented Aug. 7, I900.

H. A. HANNUM. PROCESS OF FORMING PINKING CUTTEBS.

(Application flla'd In 25, 1899.)

(N0 ludel.)

WITNESSES: INVENTOR A; ATTORNEY minis PETERS cov Pnmau'rnu, WASHINGTON u c UNITED STATES PATENT OFFICE.

HENRY A. I-IANNUM, OF OAZENOVIA, NEW YORK.

PROCESS OF FORMING PlNKlNG-CUTTERS.

SPECIFICATION forming part of Letters Patent N 0. 655,484, dated August 7, 1900.

Application filed March 25, 1899.

tion.

This invention relates to the pinking-cutter illustrated in my prior application for Letters Patent, Serial N 0. 681,715, filed May 25, 1898; and it consists in the novel process of constructing said cutters as described in said application and as hereinafter described and claimed.

In the accompanying drawings, Figure lis a plan view of a pinking-cutter formed by my improved process. Fig. 2 is an edge view of the same. Fig. 3 is a fractional side view of the dies with the cutter interposed. Fig. 4; is a vertical transverse section of said dies; and Fig. 5 is a plan View of a piece of fabric, showing the effect of the pinking-cutter.

This invention relates specially to the process of forming from a blank of sheet-steel a' circular pinking-cutter having its edge curved serpentine and successively crimped or zigzag-shaped.

In practicing my invention I found that in order to produce a pinking-outter of the aforesaid form in a perfect condition it is absolutely necessary to avoid straining and weakening the edge or marginal portion of the blank during the operation of heating and bending the same into the serpentine or zigzag shape, and for that reason the entire blank must be maintained of a uniform thick ness from the center to the extreme edge thereof until the aforesaid shaping of the cutter has been perfected.

An attempt to make a cutter of the aforesaid shape by sharpening or beveling the edge of the blank before heating and crimping the same will always prove a failure in the production of a perfect cutter, owing to the fact that the beveled and thus-thinned edge of the blank becomes excessively heated in th e proc ess of heating the blank sufficiently to allow the entire marginal portion thereof to be bent Serial No. 710,454. (No model.)

into successive reverse curves and crimped zigzag. In addition to the excessive heating of the edge of the blank the bending of said edge reduces the thickness thereof and weakens the same, so as to render it incapable of resisting the strain incident to the stretching and distorting it is subjected to in pressing it into the aforesaid shape.

The object of this invention is to obviate these defects and to produce a perfect and durable pinking-cutter having its cutting edge and marginal portion curved and crimped zigzag, as herein shown.

In practicing my invention I stamp the disk at or circular blank out of suitable sheetsteel, and after heating said blank to a proper temperature I place it between dies 01 d of a drop-press, which dies are shaped to press the marginal portion of the blank into successive arches a, extending around the periphery of the blank, and at the same time crimp said portion of the blank, as shown at (0 After the blank has been thus shaped and removed from the dies and tempered I grind and sharpen the edges of the erimps by filing or grinding said edges, preferably by means of an emery-wheel having a V-shaped peripheral face, against which the successive edges of the crimps are held.

By the described process I am enabled to form on the periphery of the cutter a perfect continuous zigzag cutting edge which has not been injured or weakened by heating the metal.

What I claim as my invention is- The improved method of manufacturing a circular pinking-cutter by stamping a circular blank out of sheet-steel, maintaining said blank of a uniform thickness from the center to the extreme edge thereof, then heating said blank and while in this condition crimping and curving the marginal portion thereof and imparting the final shape to the blank, then tempering and hardening the blank, and subsequently beveling the crimped edges of the tempered blank as set forth.

HENRY A. HANNUM.

Witnesses:

J. J. LAASS, H. B. SMITH. 

